Air bleeding pipe joint

ABSTRACT

An air bleeding pipe joint has a pair of connection pipe portions inserted and connected to a circulation piping of engine cooling water, a branch pipe portion branched from the connection pipe portions and having an air bleeding hole in an inner side thereof, and a plug body detachably mounted to the branch pipe portion, and opening and closing the air bleeding hole. The air bleeding pipe joint discharges air within the circulation piping to the outside by opening the air bleeding hole. The plug body is attached to the branch pipe portion by using an elastic locking structure or an embedding structure.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an air bleeding pipe joint connected to a circulation piping for engine cooling water and provided for executing an air bleeding within the circulation piping.

2. Description of Related Art

When air is confined within the circulation piping at a time of injecting the engine cooling water within the circulation piping for the engine cooling water of a motor vehicle, an injecting performance of the engine cooling water is deteriorated. Accordingly, an air bleeding portion has been conventionally provided in the middle of the circulation piping.

A technique that the air bleeding portion mentioned above is provided is disclosed, for example, in the following patent document 1.

As a means for providing the circulation piping of the engine cooling water with the air bleeding portion mentioned above, the following patent document 2 discloses an air bleeding pipe joint that has a pair of connection pipe portions inserted and connected to the circulation piping, a branch pipe portion branched from the connection pipe portions and having an air bleeding hole in an inner side, and a plug body detachably mounted to the branch pipe portion so as to open and close the air bleeding hole, and discharges the air within the circulation piping to the outside by opening the air bleeding hole. The air bleeding pipe joint is provided on a circulation path of engine cooling water, that is, in the middle of the circulation piping.

FIG. 13 shows a concrete example thereof.

In the drawing, reference numeral 200 denotes a heater hose (a part of a piping for introducing cooling water heated by an engine to a heating heater core within a passenger room) constituting a part of the circulation piping of the engine cooling water, and reference numeral 202 denotes an air bleeding pipe joint connected to the heater hose 200.

The air bleeding pipe joint 202 is formed in a T-shape as shown in FIG. 13(B), has a pair of connection pipe portions 204 and a branch pipe portion 206 branched therefrom, the connection pipe portions 204 are inserted and connected to a pair of heater hoses 200, and are further fixed by a hose clamp 208 (refer to FIG. 13(A)).

The branch pipe portion 206 has an air bleeding hole 210 in the inner side thereof, and the air bleeding pipe joint 202 discharges the air within the circulation piping to the outside through the air bleeding hole 210.

Reference numeral 212 denotes a plug body for opening and closing the air bleeding hole 210. The plug body 212 has a male thread portion 214, and the male thread portion 214 is screwed into a female thread portion 216 on the inner surface of the branch pipe portion 206, so that the plug body 212 is attached to the branch pipe portion 206.

The plug body 212 has a large-diameter head portion 217, and the head portion 217 protrudes to an upper side in an axial direction and in an axially perpendicular direction from the branch pipe portion 206.

The head portion 217 is formed in a hexagonal shape in a plan view as shown in FIG. 13(C), and has three pairs of tool engagement surfaces 220-1, 220-2 and 220-3 which are in parallel with each other along an outer periphery.

In the structure shown in FIG. 13, the plug body 212 is attached to and detached from the branch pipe portion 206 by pinching the engagement surfaces 220-1, 220-2 and 220-3 from the axially perpendicular direction by a tool, such as a spanner or the like and rotating the tool.

In this case, a cross-shaped groove 218 for engaging with the leading end of a screw driver is formed in a top surface of the head portion 217.

In this case, in recent years, various parts and devices are in close formation within the engine room, and a space within the engine room is extremely limited. Accordingly, it is necessary to execute an attaching and detaching work of the plug body 212 in the air bleeding pipe joint 202 within the limited narrow working space.

However, in the air bleeding pipe joint 202 shown in FIG. 13, it is necessary to rotate the plug body 212 while avoiding an interference with the other parts or the like within the narrow working space by using a long tool, and therefore, there is a problem that a workability is deteriorated.

Further, if the plug body 212 is fastened too strongly by an excessive force with the tool, there is a risk that the thread or the head portion 217 is crushed or deformed, or a chip, a crack or the like is generated in the thread or the head portion 217, in some case.

Further, in the case of the air bleeding pipe joint 202 shown in FIG. 13, if the joint is made of a resin, a play is generated in a thread fitting portion due to a long-term aging, so that there is a risk that a liquid leakage occurs therefrom, or the plug body 212 comes off.

Further, it is required to make the air bleeding pipe joint as compact as possible, however, since the air bleeding pipe joint 202 shown in FIG. 13 is structured such that the plug body 212 protrudes in each of the axial direction and the axially perpendicular direction from the branch pipe portion 206, a branch length of an entire plug body 212 and branch pipe portion 206 is elongated, and the air bleeding pipe joint 202 itself becomes bulky, so that the air bleeding pipe joint 202 occupies a wide space within the engine room.

Further, when executing other works in the periphery of the air bleeding pipe joint 202, the tool or the like is brought into contact or touch with the plug body 212. As a result, there is a risk that the plug body 212 is loosened or comes off, or the damage such as the chip, the crack or the like is generated in the plug body 212 by an impact.

Further, in the case of the air bleeding pipe joint 202 shown in FIG. 13, there is a problem that it is troublesome to check whether or not the plug body 212 is completely closed.

[Patent Document 1]

JP, A, 61-93225

[Patent Document 2]

JP, A, 2004-161163

The present invention is made by taking the circumstances mentioned above into consideration, and an object of the present invention is to provide an air bleeding pipe joint which can cope with the problem mentioned above relating to the damage of the plug body, and has less risk that the plug body is damaged.

In accordance with one aspect of the present invention, there is provided an air bleeding pipe joint for bleeding air within a circulation piping of engine cooling water which enables attaching and detaching of the plug body easily within a limited narrow working space.

Further, in accordance with one aspect of the present invention, there is provided an air bleeding pipe joint which is structured compact so that the air bleeding pipe joint does not occupy a wide space within the engine room.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided an air bleeding pipe joint comprising: (a) a pair of connection pipe portions inserted and connected to a circulation piping of engine cooling water; (b) a branch pipe portion branched from the connection pipe portion and having an air bleeding hole in the inner side thereof; (c) a plug body detachably mounted to the branch pipe portion, and opening and closing the air bleeding hole; the air bleeding pipe joint discharging air within the circulation piping to the outside by opening the air bleeding hole, wherein the plug body is attached to the branch pipe portion by using an elastic locking structure or an embedding structure.

In the case of using the elastic locking structure, the elastic locking structure can be set such that an elastic locking hook is provided to one of the plug body and the branch pipe portion, a locking portion elastically locking the elastic locking hook is provided to the other, and the plug body can be attached to and detached from the branch pipe portion, by locking the elastic locking hook to the locking portion and canceling the locking.

The structure may be made such that the plug body is provided with an insertion portion to the branch pipe portion, the elastic locking hook is formed in the insertion portion, and the locking portion is provided at a corresponding position of the branch pipe portion. Further, the structure can be made such that the branch pipe portion is provided with an operation window for canceling the elastic locking of the elastic locking hook to the locking portion. Further, the structure can be made such that a one-way annular come-off prevention tooth having a saw-tooth cross-sectional shape is formed in an outer peripheral surface of the connection pipe portion, the come-off prevention tooth allows a relative movement of the connection pipe portion in an inserting direction with respect to the circulation piping, and eats into an inner surface of the circulation pipe in a reverse direction so as to achieve a come-off prevention.

Further, in the case of using the embedding structure, the embedding structure can be set such that a female thread portion is provided in an inner surface of the branch pipe portion, a male thread portion is provided in the plug body, they are coupled by screw, an engagement concave portion for engaging with a tool is provided in a top surface of the plug body, and the plug body is entirely embedded to an inner portion of or inside the branch pipe portion.

The structure can be made such that the engagement concave portion is formed in a hexagonal shape. Further, the structure can be made such that a large-diameter head portion is provided in the plug body, an accommodation portion accommodating the head portion is provided in the branch pipe portion, and a bottom surface of the accommodation portion is formed as a stopper surface defining a screwing amount of the plug body. Further, the structure can be made in this case such that a one-way annular come-off prevention tooth having a saw-tooth cross-sectional shape is formed in an outer peripheral surface of the connection pipe portion, the come-off prevention tooth allows a relative movement of the connection pipe portion in an inserting direction with respect to the circulation piping, and eats into an inner surface of the circulation pipe in a reverse direction so as to achieve a come-off prevention.

In accordance with the present invention, the plug body is attached to the branch pipe portion by using the elastic locking structure or the embedding structure. In this case, if the elastic locking structure is employed, it is possible to prevent the plug body from being fastened too strongly more than necessary by the tool. Accordingly, it is possible to solve the problem that the damage such as the chip, the crack or the like is generated in the plug body due to the fastening of the plug body by the excessive force. Further, if the embedding structure is employed, the plug body does not protrude in both of the axial direction and the axially perpendicular direction from the branch pipe portion under the attached state. Accordingly, it is possible to prevent the tool or other members from being brought into contact with the plug body of the air bleeding pipe joint during the work in the periphery so as to generate the damage such as the chip, the crack or the like in the plug body.

Further, since the elastic locking structure does not employ the structure of attaching the plug body to the branch pipe portion on the basis of the fitting of the threads, there is not generated the problem that the play is generated in the fitting portion of the threads due to the long-term aging, and it is possible to solve the problem that the liquid leakage from the portion occurs, or the plug body comes off. Further, by employing the embedding structure, the plug body does not protrude in both of the axial direction and the axially perpendicular direction from the branch pipe portion under the attached state, it is possible to reduce the branch height (the branch length) of the entire plug body and branch pipe portion, and it is possible to make the air bleeding pipe joint more compact in comparison with the conventional structure. Accordingly, it is possible to reduce the space in which the air bleeding pipe joint occupies within the engine room. Further, since the embedding structure is structured in such a manner that the plug body is embedded in the inner portion of or inside the branch pipe portion under the attached state, it is possible to easily check whether or not the plug body is securely or correctly attached to the branch pipe portion by checking that the plug body does not protrude from the branch pipe portion by touching by hand, that is, without any visual observation at a time of screwing the plug body to the branch pipe portion so as to attach. In the elastic locking structure wherein an upper surface of the plug body or head portion of the plug body and an upper surface of the branch pipe portion are in a state of being positioned at the same height when the plug body is securely or correctly attached to the branch pipe portion, it is similarly possible to easily check secure or correct attachment of the plug body by touching by hand.

Further, in the case that the elastic locking structure is structured such that the elastic locking hook is provided in one of the plug body and the branch pipe portion, the locking portion elastically locking the elastic locking hook is provided in the other, and the plug body is attached to and detached from the branch pipe portion by locking the elastic locking hook to the locking portion and canceling the locking, it is possible to easily attach the plug body to the branch pipe portion through one-touch operation on the basis of the locking between the elastic locking hook and the locking portion, only by pressing the plug body against the branch pipe portion while holding the plug body by hand. Further, it is possible to easily take out the plug body from the branch pipe portion only by canceling the locking of the elastic locking hook with the locking portion. Further, it is possible to easily execute the attaching and detaching work of the plug body within the limited narrow working space within the engine room.

In this case, the structure can be made such that the insertion portion to the branch pipe portion is provided in the plug body, the elastic locking hook is formed in the insertion portion, and the locking portion is provided at the corresponding position in the branch pipe portion. Further, in the case that the branch pipe portion is provided with the operation window for canceling the elastic locking of the elastic locking hook with the locking portion, it is possible to easily cancel the locking of the elastic locking hook with respect to the locking portion through the operation window, at a time of taking out the plug body from the branch pipe portion.

The structure can be made such that the insertion portion is provided with a fitting shaft portion, the fitting shaft portion is fitted to an inner peripheral surface of the branch pipe portion, an annular seal member is installed to an outer peripheral surface of the fitting shaft portion, and a seal member seals between the outer peripheral surface of the fitting shaft portion and the inner peripheral surface of the branch pipe portion.

Further, the structure can be made such that a one-way annular come-off prevention tooth having a saw-tooth cross-sectional shape is formed in an outer peripheral surface of the connection pipe portion or a pair of connection pipe portions, the come-off prevention tooth allows a relative movement of the connection pipe portion in an inserting direction with respect to the circulation piping, and eats into an inner surface of the circulation pipe in a reverse direction so as to achieve a come-off prevention. In accordance with the structure mentioned above, it is possible to connect and fix the air bleeding pipe joint to the circulation piping only by pressure inserting the connection pipe portion to the inner portion of or inside the circulation piping, and it is possible to omit the hose clamp 208 for fixing the air bleeding pipe joint and the circulation piping as shown in FIG. 13.

Further, the embedding structure can be structured such that the female thread portion is provided in the inner surface of the branch pipe portion, the male thread portion is provided in the plug body, they are coupled by screw, the engagement concave portion for engaging with the tool is provided in the top surface of the plug body, and the plug body is entirely embedded to the inner portion of or inside the branch pipe portion. In accordance with the structure mentioned above, it is possible to easily detach the plug body from the branch pipe portion by engaging the tool with the engagement concave portion and rotating the tool.

In this case, the engagement concave portion can be formed in the hexagonal shape.

In accordance with the structure mentioned above, it is possible to easily rotate the plug body in the reduced working space by using the hexagonal rod-shaped general-purpose tool so as to attach and detach the plug body to and from the branch pipe portion.

Further, the structure can be made such that the large-diameter head portion is provided in the plug body, the accommodation portion accommodating the head portion is provided in the branch pipe portion, and the bottom surface of the accommodation portion is formed as the stopper surface defining the screwing amount of the plug body. In accordance with the structure mentioned above, it is possible to securely screw the plug body which is in the embedded state in the inner portion of or inside the branch pipe portion under the screwed state to the defined screwing or screw inserting position on the basis of a screwing regulation effect by the bottom surface of the accommodation portion, and it is possible to prevent the excessive screwing. For example, an upper surface (top surface) of the head portion and an upper surface of the branch pipe portion may form a flush surface, or the upper surface of the head portion may be located at the same height as the upper surface of the branch pipe portion, or on a surface flush with the upper surface of the branch pipe portion when the plug body is securely or correctly attached. With such structure, it is possible to check the plug body is securely or correctly attached to the branch pipe portion while checking that the plug body does not protrude from the branch pipe portion by touching by hand.

Now, a description will be given in detail of an embodiment in accordance with the present invention on the basis of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory view showing a portion to which a first air bleeding pipe joint in accordance with an embodiment of the present invention is applied;

FIG. 2 is a perspective view of the first air bleeding pipe joint in accordance with the embodiment;

FIG. 3 is a cross-sectional view (with a partly side elevational view) of the first air bleeding pipe joint in accordance with the embodiment;

FIG. 4 is the other cross-sectional view of the first air bleeding pipe joint in accordance with the embodiment;

FIG. 5 is a perspective view showing the first air bleeding pipe joint in accordance with the embodiment in a state in which a plug body is detached;

FIG. 6 is a cross-sectional view showing the first air bleeding pipe joint in accordance with the embodiment in the state in which the plug body is detached;

FIG. 7 is an explanatory view showing a portion to which a second air bleeding pipe joint in accordance with an embodiment of the present invention is applied;

FIG. 8 is a perspective view of the second air bleeding pipe joint in accordance with the embodiment in a state in which a plug body is attached;

FIG. 9 is a cross-sectional view of the second air bleeding pipe joint in accordance with the embodiment;

FIG. 10 is a perspective view showing the second air bleeding pipe joint in accordance with the embodiment in a state in which the plug body is detached;

FIG. 11 is a cross-sectional view showing the second air bleeding pipe joint in accordance with the embodiment in the state in which the plug body is detached.

FIG. 12 is an explanatory view showing a method of attaching and detaching the plug body in the second air bleeding pipe joint in accordance with the embodiment;

FIG. 13(A) is a perspective view showing an example of a conventional air bleeding pipe joint;

FIG. 13(B) is a half cross-sectional front elevational view showing an example of the conventional air bleeding pipe joint; and

FIG. 13(C) is a plan view showing an example of the conventional air bleeding pipe joint.

DESCRIPTION OF PREFERABLE EMBODIMENT

In FIG. 1, reference numeral 10 denotes a circulation piping of engine cooling water, reference numeral 10-1 denotes a radiator side piping communicating an engine 12 with a radiator 14, and reference numeral 10-2 denotes a heater side piping communicating the engine 12 with a heating heater core 16 within a passenger room.

In the drawing, reference numeral 18-1 denotes a rubber upper radiator hose constituting a part of the circulation piping 10, specifically a part of the radiator side piping 10-1, and reference numeral 18-2 denotes a lower radiator hose.

Further, reference numeral 20-1 denotes a rubber upper heater hose constituting a part of the circulation piping 10, specifically a part of the heater side piping 10-2, and reference numeral 20-2 denotes a lower heater hose.

Further, reference numeral 22 denotes a water pump, and reference numeral 23 denotes a thermo valve having a thermostat function.

In FIG. 1, a first air bleeding pipe joint 24 in accordance with the present embodiment is connected between the upper heater hoses (hereinafter, refer simply to as the heater hoses or the heater hose) 20-1 and 20-1.

FIGS. 2 to 6 show a specific structure of the first air bleeding pipe joint 24.

The first air bleeding pipe joint 24 is made of a resin, is formed in a T-shape as shown in FIGS. 2 and 3, and has a pair of connection pipe portions 26, and a branch pipe portion 28 perpendicularly rising therefrom.

Each of a pair of connection pipe portions 26 corresponds to a portion inserted and connected into the heater hose 20-1, and an annular come-off prevention tooth 30 is provided at each of two positions in an axial direction in an outer peripheral surface thereof.

The come-off prevention tooth 30 is formed in a saw-tooth shaped cross-sectional shape, and is formed as a one-way penetration or stop tooth which allows a relative movement in an inserting direction with respect to the heater hose 20-1, and eats into inner surfaces thereof in a reverse direction so as to achieve a come-off prevention.

Accordingly, the first air bleeding pipe joint 24 can be connected and fixed only by pressure inserting each of the connection pipe portions 26 to an inner portion of or inside the heater hose 20-1, and does not particularly require the fixing by the hose clamp 208 as shown in FIG. 13.

The branch pipe portion 28 has a root side small pipe portion 32 and an upper large pipe portion 34, and has an air bleeding hole 36 in an inner side thereof as shown in FIGS. 4 and 6.

The air in the inner portion of the circulation piping 10 is discharged to the outside through the air bleeding hole 36.

In FIGS. 2 and 4, reference numeral 38 denotes a plug body which is detachably mounted to the branch pipe portion 28, and opens or closes the air bleeding hole 36. The plug body 38 has an insertion portion 40 inserted into the branch pipe portion 28 in an axial direction, and a head portion 42 exposed to the outside.

A lower portion of the insertion portion 40 is structured as a fitting shaft portion 44 which is inserted to the small pipe portion 32 in the branch pipe portion 28 downward in the drawing so as to be fitted to an inner surface of the small pipe portion 32, and has a circular cross-sectional shape corresponding to an inner peripheral surface of the small pipe portion 32.

An annular O-ring groove is formed in an outer peripheral surface of the fitting shaft portion 44, and an O-ring 46 corresponding to an annular seal member is installed and held therein.

Further, the structure is constructed such that the O-ring 46 seals between an outer peripheral surface of the fitting shaft portion 44 and the inner peripheral surface of the small pipe portion 32.

On the other hand, the upper portion of the insertion portion 40 is formed in a C-shaped or horse-shoe cross-section, and a pair of elastic locking hooks 48 are structured by a part of a peripheral wall portion thereof.

In this case, an elastic deforming performance is applied to the elastic locking hook 48 by a slot formed in the peripheral wall portion.

In this case, in the elastic locking hook 48, there are formed an inclined guide surface 50 executing a guide for insertion or contraction at a time of press inserting the plug body 38 downward, and a locking surface 52 in an axially perpendicular direction.

On the other hand, a locking portion 54 is provided in the large pipe portion 34 in the branch pipe portion 28 in correspondence to each of a pair of elastic locking hooks 48, and an operation window 56 for canceling the locking of the elastic locking hook 48 with respect to the locking portion 54 is provided in a lower side of the locking portion 54 in such a manner as to pass through the large pipe portion 34 in an inside and outside direction.

In this case, as shown in FIG. 5, a notch portion 58 is provided in an upper end portion of the large pipe portion 34 in the branch pipe portion 28, and the head portion 42 of the plug body 38 is accommodated in the notch portion 58.

FIG. 2 shows a state in which the head portion 42 is accommodated in the notch portion 58. As shown in the drawing, an upper surface of the head portion 42 and an upper surface of the branch pipe portion 28 are in a state of being positioned at the same height at this time.

In other words, the upper surface of the head portion 42 and the upper surface of the branch pipe portion 28 form a flush surface, or the upper surface of the head portion 42 is located on a surface flush with the upper surface of the branch pipe portion 28.

Further, an outer peripheral surface of the head portion 42 and an outer peripheral surface of the branch pipe portion 28, in detail, the outer peripheral surface of the large pipe portion 34 are located on a common cylindrical outer surface.

Next, a description will be given on an operation of the first air bleeding pipe joint 24 in accordance with the present embodiment.

FIGS. 5 and 6 show a state in which the plug body 38 is detached. When pressing the plug body 38 into the branch pipe portion 28 from this state downward in the drawing, the elastic locking hook 48 is temporarily contracted and deformed elastically in a direction coming close to each other on the basis of the guiding operation of the guide surface 50. And, then the elastic locking hook 48 passes downward through the locking portion 54, and is expanded again by an elastic restoring force so as to be locked with the locking portion 54, and the fitting shaft portion 44 in the lower portion of the insertion portion 40 is simultaneously in a state of being fitted to the small pipe portion 32 of the branch pipe portion 28, and the air bleeding hole 36 in the inner side of the branch pipe portion 28 is in a closed state.

Even if a pulling force in an upper side in the drawing is applied to the plug body 38 in this state, the plug body 38 does not get out of the branch pipe portion 28 on the basis of the locking operation between the elastic locking hook 48 and the locking portion 54.

As mentioned above, in accordance with the embodiment, it is possible to easily attach the plug body 38 to the branch pipe portion 28 only by pressing the plug body 38 downward in the drawing, and set the air bleeding hole 36 in the closed state.

On the other hand, in the case that there is generated the necessity of detaching the plug body 38 from the branch pipe portion 28 so as to open the air bleeding hole 36, it is preferable to contract and deform a pair of elastic locking hook 48 in the contracting direction through the operation window 56 so as to cancel the locking of the elastic locking hook 48 with respect to the locking portion 54 and pull out the plug body 38 upward in the drawing under this state.

In the present embodiment, it is possible to easily attach the plug body 38 to the branch pipe portion 28 through one-touch operation on the basis of the locking between the elastic locking hook 48 provided in the upper portion of the insertion portion 40 of the plug body 38 and the locking portion 54 provided in the corresponding position in the branch pipe portion 28, only by pressing the plug body 38 against the branch pipe portion 28 while holding the plug body 38 by hand.

Further, since the branch pipe portion 28 is provided with the operation window 56 for canceling the elastic locking of the elastic locking hook 48, it is possible to easily take out the plug body 38 from the branch pipe portion 28 only by canceling the locking of the elastic locking hook 48 with the locking portion 54 through the operation window 56.

In accordance with the structure mentioned above, it is possible to attach and detach the plug body 38 to and from the branch pipe portion 28 without using the tool, and it is possible to easily execute the attaching and detaching work of the plug body 38 within the limited narrow working space within the engine room.

Further, since it is possible to prevent the plug body 38 from being fastened too strongly more than necessary by the tool, it is possible to solve the problem that the damage such as the chip, the crack or the like is generated in the plug body 38 due to the fastening of the plug body 38 by the excessive force.

Further, since the plug body 38 is not attached to the branch pipe portion 28 on the basis of the fitting of the threads in the present embodiment, there is not generated the problem that the play is generated due to the long-term aging in the fitting portion of the threads, and it is possible to prevent the risk that the liquid leakage occurs from the portion, or the plug body 38 is detached.

In FIG. 7, the portions to which the same reference numerals as those of FIG. 1 are attached have the same structures as those of FIG. 1.

In FIG. 7, a second air bleeding pipe joint 60 in accordance with the present embodiment is connected between the heater hoses 20-1 and 20-1.

FIGS. 8 to 11 show a specific structure of the second air bleeding pipe joint 60.

The second air bleeding pipe joint 60 is made of a resin, is formed in a T shape as shown in FIGS. 8 and 10, and has a pair of connection pipe portions 62, and a branch pipe portion 64 perpendicularly rising therefrom.

A pair of connection pipe portions 62 correspond to a portion inserted and connected into the heater hose 20-1 as shown in FIG. 12, and a bulge portion 66 corresponding to an annular protruding portion is provided in a leading end portion and an outer peripheral surface thereof.

The branch pipe portion 64 has an air bleeding hole 68 in an inner side thereof as shown in FIGS. 9 and 11, and discharges the air within the circulation piping 10 to the outside through the air bleeding hole 68.

A female fitting portion 70 having a circular inner surface is formed in the branch pipe portion 64, a female thread portion 72 is provided in an inner peripheral surface in an upper side of the female fitting portion 70, and a concave accommodation portion 78 accommodating a head portion 76 of a plug body 74 mentioned below is provided in an upper side of the female thread portion 72.

A bottom surface of the accommodation portion 78 is formed as a stopper surface 80 defining a screwing amount of the plug body 74.

In FIGS. 8 to 10, reference numeral 74 denotes a plug body which is detachably mounted to the branch pipe portion 64, and opens or closes the air bleeding hole 68. The plug body 74 has a fitting shaft portion 82 inserted into the female fitting portion 70 of the branch pipe portion 64 downward in the drawing so as to be fitted.

An annular O-ring groove is formed in an outer peripheral surface of the fitting shaft portion 82, and an O-ring 84 corresponding to an annular seal member is installed and held therein.

The fitting shaft portion 82 is fitted to a female fitting portion 70 via the O-ring 84, and the O-ring 84 seals between them in a liquid tight manner.

The plug body 74 is further provided with a male thread portion 86 in an upper side of the fitting shaft portion 82, and the male thread portion 86 of the plug body 74 is screwed into a female thread portion 72 of the branch pipe portion 64.

The plug body 74 has a large-diameter flat plate-like head portion 76 in an upper side of the male thread portion 86, and a hexagonal engagement concave portion 88 for engaging with the tool is provided in a top surface of the head portion 76.

FIGS. 8 and 9 show a state in which the plug body 74 is screwed into the branch pipe portion 64 so as to be attached. As shown in these drawings, the plug body 74 is completely embedded within the branch pipe portion 64 in the attached state.

At this time, the head portion 76 of the plug body 74 is accommodated in the accommodation portion 78 in a state in which the lower surface thereof is brought into contact with a bottom surface of the accommodation portion 78, that is, a stopper surface 80.

Further, the top surface thereof is in a state of forming the same flat surface as the upper surface of the branch pipe portion 64.

In other words, the top surface of the plug body 74 and the upper surface of the branch pipe portion 64 are in a state of forming the flush surface, or the top surface of the plug body 74 is located on a surface flush with the upper surface of the branch pipe portion 64.

In this case, a taper portion 90 is formed between the fitting shaft portion 82 and the male thread portion 86 in the plug body 74.

Next, a description will be given of an operation of the second air bleeding piping joint 60 in accordance with the present invention.

FIGS. 10 and 11 show a state in which the plug body 74 is detached from the branch pipe portion 64. In order to attach the plug body 74 to the branch pipe portion 64 from this state so as to close the air bleeding hole 68, the plug body 74 is pressed to the branch pipe portion 64 downward in the drawing, a leading end portion of a hexagonal rod-like tool (a hexagonal wrench) 92 is inserted to and engaged with a hexagonal engagement concave portion 88 formed in the top surface of the head portion 76 as shown in FIG. 12, and the plug body 74 is rotated by the tool 92.

Accordingly, the male thread portion 86 of the plug body 74 is screwed into the female thread portion 72, and there is obtained a state in which the head portion 76 is finally accommodated in the accommodation portion 78 of the branch pipe portion 64. In this case, the lower surface of the head portion 76 is brought into contact with the stopper surface 80 of the accommodation portion 78 and a further screwing is regulated.

In this state, the plug body 74 is in a state in which the entire plug body 74 is embedded to an inner portion of or inside the branch pipe portion 64, and there is obtained a state in which the top surface of the head portion 76 is positioned at the same height as the upper surface of the branch pipe portion 64.

In this case, the air bleeding hole 68 of the branch pipe portion 64 is in a state of being closed by the plug body 74.

On the other hand, in order to detach the plug body 74 from the branch pipe portion 64, it is preferable to execute the reverse operation to that mentioned above. In other words, when engaging the leading end portion of the tool 92 with the engagement concave portion 88 of the head portion 76 of the plug body 74 and rotating the tool 92 in the reverse direction to that mentioned above, the plug body 74 is pushed out upward in the drawing on the basis of a screw feeding operation between the male thread portion 86 and the female thread portion 72, the screw engagement between the male thread portion 86 and the female thread portion 72 is finally canceled, and the plug body 74 can be taken out upward in the drawing from the branch pipe portion 64.

As mentioned above, in accordance with the present embodiment, since the plug body 74 is entirely embedded to the inner portion of the branch pipe portion 64 in the attached state, and the plug body 74 does not protrude to both of the axial direction and the axially perpendicular direction from the branch pipe portion 64, it is possible to reduce the branch height of the entire plug body 74 and branch pipe portion 64, and it is possible to make the second air bleeding pipe joint 60 more compact in comparison with the conventional structure.

Further, it is possible to prevent the tool or other members from being brought into contact with the plug body 74 of the second air bleeding pipe joint 60 during the work in the periphery so as to generate the damage such as the chip, the crack or the like in the plug body 74.

Further, since the plug body 74 is embedded to the inner portion of or inside the branch pipe portion 64 in the attached state, it is possible to check that the plug body 74 does not protrude from the branch pipe portion 64 by touching by hand at a time of screwing the plug body 74 into the branch pipe portion 64 so as to attach, whereby it is possible to easily check whether or not the plug body 74 is securely screwed into the branch pipe portion 64 without any visual observation.

Further, since the top surface of the plug body 74 is provided with the hexagonal engagement concave portion 88 for engaging with the tool 92, it is possible to easily detach the plug body 74 from the branch pipe portion 64 by engaging the tool 92 with the engagement concave portion 88 so as to rotate. In other words, it is possible to easily attach and detach the plug body 74 to and from the branch pipe portion 64 within the reduced working space by using the hexagonal rod-shaped general-purpose tool 92.

Further, in the present embodiment, since the plug body 74 is provided with the large-diameter head portion 76, the branch pipe portion 64 is provided with the accommodation portion 78 accommodating the head portion 76, and the bottom surface of the accommodation portion 78 is formed as the stopper surface 80 defining the screwing amount of the plug body 74, it is possible to securely screw the plug body 74 which is in the embedded state in the inner portion of, inside, or within the branch pipe portion 64 in the screwed state, to the defined screwing or screw inserting position on the basis of the screw regulating operation by the stopper surface 80 of the accommodation portion 78, and it is possible to prevent the excessive screwing.

The description is in detail given above of the embodiments in accordance with the present invention, however, they are only provided as exemplification, and the present invention can be structured in accordance with variously modified aspects within the scope of the invention. The air bleeding pipe joint in accordance with the present invention, for example, can be connected to the upper radiator hose 18-1 in FIG. 1 or 7 so as to achieve an air bleeding. 

1. An air bleeding pipe joint, comprising: (a) a pair of connection pipe portions inserted and connected to a circulation piping of engine cooling water; (b) a branch pipe portion branched from said connection pipe portion and having an air bleeding hole in an inner side thereof; (c) a plug body detachably mounted to said branch pipe portion, and opening and closing said air bleeding hole; the air bleeding pipe joint discharging air within said circulation piping to the outside by opening said air bleeding hole, wherein said plug body is attached to said branch pipe portion by using an elastic locking structure or an embedding structure.
 2. An air bleeding pipe joint as claimed in claim 1, wherein said plug body is attached to said branch pipe portion by using said elastic locking structure, and said elastic locking structure is structured such that an elastic locking hook is provided in one of said plug body and said branch pipe portion, a locking portion elastically locking said elastic locking hook is provided in the other, and said plug body is capable of being attached to and detached from said branch pipe portion, by locking said elastic locking hook to said locking portion and canceling the locking.
 3. An air bleeding pipe joint as claimed in claim 2, wherein said plug body has an insertion portion to said branch pipe portion, said elastic locking hook is provided in said insertion portion, and said locking portion is provided at a corresponding position of said branch pipe portion.
 4. An air bleeding pipe joint as claimed in claim 3, wherein said branch pipe portion is provided with an operation window for canceling the elastic locking of said elastic locking hook to said locking portion.
 5. An air bleeding pipe joint as claimed in claim 2, wherein a one-way annular come-off prevention tooth having a saw-tooth cross-sectional shape is provided in an outer peripheral surface of said connection pipe portion, said come-off prevention tooth allows a relative movement of said connection pipe portion in an inserting direction with respect to said circulation piping, and eats into an inner surface of said circulation pipe in a reverse direction so as to achieve a come-off prevention.
 6. An air bleeding pipe joint as claimed in claim 1, wherein said plug body is attached to said branch pipe portion by using said embedding structure, and said embedding structure is structured such that a female thread portion is provided in an inner surface of said branch pipe portion, a male thread portion is provided in said plug body, they are coupled by screw, an engagement concave portion for engaging a tool is provided in a top surface of said plug body, and said plug body is entirely embedded inside said branch pipe portion.
 7. An air bleeding pipe joint as claimed in claim 6, wherein said engagement concave portion is formed in a hexagonal shape.
 8. An air bleeding pipe joint as claimed in claim 6, wherein a large-diameter head portion is provided in said plug body, an accommodation portion accommodating said head portion is provided in said branch pipe portion, and a bottom surface of said accommodation portion is formed as a stopper surface defining a screwing amount of said plug body. 